We are interested in how bacteria and bacterial products shape the development of subsequent innate and adaptive immune responses with the goal of understanding how these host-microbe interactions influence pathogenesis of infections, autoimmunity, allergy, and cancer. In 2015, we have continued our focus on host defense against the bacterial pathogen Staphylococcus aureus, uncovering the role of innate and adaptive immune pathways in mediating protective and detrimental responses to infection using mouse models. We have also begun clinical studies to characterize these responses in humans. In addition, in 2015 we have identified influences of host-commensal interactions on susceptibility to infections and immune responses. With these studies we have enhanced our understanding of the mechanisms controlling skin and mucosal host defense and identified potential pathways that can be targeted to enhance efficacy of vaccines and therapies against cancer, infection, and immune-mediated diseases.